Controlling input and output of different program

rkrasowski has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks, again, seems like simple problem but I can't solve this. I would like to control one program (that is normally controlled from terminal) with perl program. So , I understand there are few ways of managing it. I started with reading output of the program using pipes and I can not do it. Here is an example of what I am talking about:

#
open my $READ, "-|",  "./dialog.pl";
while (<$READ>)
        {
                print $_;
        }
close $READ;
[download]

Here is the dialog.pl program that I am trying to interact with:

print "How old are you? ";
my $age = <>;
print "You are $age.";
[download]

The way I understand first program will open dialog.pl program and display "How old are you?" in the terminal,but it is not the case. What is the issue here? I would like to catch output from dialog.pl , and respond to it. I also understand that I will have to fork the program to be able to do writing and reading from dialog.pl at the same time. Thanks like always. Robert

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Re: Controlling input and output of different program by jeffa (Bishop) on Mar 30, 2015 at 22:44 UTC
I was able to throw this together after taking a gander at the link provided by Anonymous Monk in this thread: `use strict; use warnings; use FileHandle; use IPC::Open2; my $pid = open2(Reader, Writer, "perl dialog.pl"); print Writer "42\n"; chomp( my $got = <Reader> ); print $got, $/;` [download] Notice the explicit use of `chomp()` as well as terminating the sent string with a newline. I recommend you alter your `dialog.pl` script to `chomp()` user input: `chomp( my $age = <> );` [download] jeffa L-LL-L--L-LL-L--L-LL-L-- -R--R-RR-R--R-RR-R--R-RR B--B--B--B--B--B--B--B-- H---H---H---H---H---H--- (the triplet paradiddle with high-hat)	[reply] [d/l] [select]
Re^2: Controlling input and output of different program by rkrasowski (Sexton) on Mar 31, 2015 at 02:16 UTC
Great, thanks a lot, I implemented your advice and it is working, link that you provided is fantastic. Thanks again Robert	[reply]
Re: Controlling input and output of different program by Anonymous Monk on Mar 30, 2015 at 22:33 UTC
Why? Error checking? perlipc has examples , although I'd avoid interactive CLI programs like this ... eew ;)	[reply]